Let us now a few things first before we get into numbers, bow weigh, and what you are bowhunting, type of hunting or 3D in other words you would not use the same set up if you were hunting bears vs 3D
He's not asking what arrow he should be shooting, just what the different spine deflections mean. Brian, The numbers you are seeing represent the spine deflection of the arrow, or the stiffness in simple terms. The higher the number (500) the weaker the arrow, the lower the number (340) the stiffer the arrow. While at a shop you will generally see 300's, 340's, 400's, and 500's. There are obvious exceptions, though. Some companies like Carbon Express like to make things interesting and do everything backwards. Their 350 spine measures .342" while their 250 spine measures .417" This is where determining your draw length, poundage, draw weight, and tip weight come into play. For your current setup I would personally put you into a .400 spine which allow the use of either 100 or 125 grain heads.
